Visual Studio Toolbox Went Empty

My Visual Studio 2010 goes weird these days, one problem is that it cannot open previously opened files when Visual Studio starts again. This is not solved yet...

Another problem is when I am designing WinForm, the tool box went empty completely, no Windows Form controls like textbox, label... at all. Luckily I find a fix:

1, Navigate to this folder

Windows 7:

C:\Users\zhang5\AppData\Local\Microsoft\VisualStudio\10.0

Windows XP:

C:\Documents and Settings\Local Settings\Application Data\Microsoft\VisualStudio\10.0

(For VS2008 it will be 9.0)

2, Delete these hidden files

"toolbox.tbd", "toolboxIndex.tbd", "toolbox_reset.tbd", "toolboxIndex_reset.tbd"

Restart Visual Studio and it recovers.